The U.S. Food and Drug Administration (FDA) is informing healthcare professionals that the Warnings and Precautions section of the labels for the 5-alpha reductase inhibitor (5-ARI) class of drugs has been revised to include new safety information about the increased risk of being diagnosed with a more serious form of prostate cancer (high-grade prostate cancer). This risk appears to be low, but healthcare professionals should be aware of this safety information, and weigh the known benefits against the potential risks when deciding to start or continue treatment with 5-ARIs in men.

The new safety information is based on FDA’s review of two large, randomized controlled trials––the Prostate Cancer Prevention Trial (PCPT) and the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial––which evaluated daily use of finasteride 5 mg versus placebo for 7 years and daily use of dutasteride 0.5 mg versus placebo for 4 years, respectively, for the reduction in the risk of prostate cancer in men at least 50 years of age. The trials demonstrated an overall reduction in prostate cancer diagnoses with finasteride 5 mg and dutasteride treatment (see Data Summary below). This overall reduction was due to a decreased incidence of lower risk forms of prostate cancer. However, both trials showed an increased incidence of high-grade prostate cancer with finasteride and dutasteride treatment.